The present invention relates to a device for increasing crankcase compression in an internal combustion engine, said engine comprising a crankshaft having main bearings and at least one crank portion including a counterweight, and filling bodies forming an annular unit together with said crank portion.
It is previously known that the performance of a two-cycle engine can be improved by increasing the crankcase compression, which can be achieved by reducing the volume of the crankcase. To this end it has been proposed to use various types of lightweight filling bodies attached to the crank portion of the crankshaft. Such a filling body is preferably shaped so as to form an annular unit together with the crank portion. The disadvantage of such known devices is that the manufacture and mounting thereof are relatively complicated and costly and they have therefore not been used to any great extent.
Although the device according to the invention is primarily intended to be used in two-cycle engines, it may also be applicable in four-cycle engines, namely such engines of the type using crankcase scavenging for the purpose of lubrication by fuel mixed with lubricating oil. Such four-cycle engines may be used for example in tools having greatly varying angular working positions preventing the use of a normal pressurized lubrication system. The invention is therefore not restricted to two-cycle engines.